Document Detail

The Rickettsia conorii autotransporter protein Sca1 promotes adherence to nonphagocytic mammalian cells.
MedLine Citation:
PMID:  20176791     Owner:  NLM     Status:  MEDLINE    
The pathogenesis of spotted fever group (SFG) Rickettsia species, including R. conorii and R. rickettsii, is acutely dependent on adherence to and invasion of host cells, including cells of the mammalian endothelial system. Bioinformatic analyses of several rickettsia genomes revealed the presence of a cohort of genes designated sca genes that are predicted to encode proteins with homology to autotransporter proteins of Gram-negative bacteria. Previous work demonstrated that three members of this family, rOmpA (Sca0), Sca2, and rOmpB (Sca5) are involved in the interaction with mammalian cells; however, very little was known about the function of other conserved rickettsial Sca proteins. Here we demonstrate that sca1, a gene present in nearly all SFG rickettsia genomes, is actively transcribed and expressed in R. conorii cells. Alignment of Sca1 sequences from geographically diverse SFG Rickettsia species showed that there are high degrees of sequence identity and conservation of these sequences, suggesting that Sca1 may have a conserved function. Using a heterologous expression system, we demonstrated that production of R. conorii Sca1 in the Escherichia coli outer membrane is sufficient to mediate attachment to but not invasion of a panel of cultured mammalian epithelial and endothelial cells. Furthermore, preincubation of a recombinant Sca1 peptide with host cells blocked R. conorii cell association. Together, these results demonstrate that attachment to mammalian cells can be uncoupled from the entry process and that Sca1 is involved in the adherence of R. conorii to host cells.
Sean P Riley; Kenneth C Goh; Timothy M Hermanas; Marissa M Cardwell; Yvonne G Y Chan; Juan J Martinez
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2010-02-22
Journal Detail:
Title:  Infection and immunity     Volume:  78     ISSN:  1098-5522     ISO Abbreviation:  Infect. Immun.     Publication Date:  2010 May 
Date Detail:
Created Date:  2010-04-19     Completed Date:  2010-05-03     Revised Date:  2014-01-03    
Medline Journal Info:
Nlm Unique ID:  0246127     Medline TA:  Infect Immun     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1895-904     Citation Subset:  IM    
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MeSH Terms
Adhesins, Bacterial / genetics,  metabolism*
Cell Adhesion*
Cercopithecus aethiops
Conserved Sequence
Endothelial Cells / microbiology
Epithelial Cells / microbiology
Escherichia coli / genetics,  pathogenicity
Gene Expression Profiling
HeLa Cells
Membrane Transport Proteins / genetics,  metabolism*
Rickettsia conorii / genetics,  pathogenicity*
Sequence Homology, Amino Acid
Vero Cells
Grant Support
2-U54-AI-057153/AI/NIAID NIH HHS; R01 AI072606/AI/NIAID NIH HHS; R01-AI072606-01/AI/NIAID NIH HHS
Reg. No./Substance:
0/Adhesins, Bacterial; 0/Membrane Transport Proteins

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